The present invention relates to a system and method for monitoring the structural health of mechanical components or structural components. For example, the present invention can be used to monitor, but by no means exclusively, the structural health of critical components of a gearbox of a helicopter.
Under normal operations, the maintenance of aircraft is usually performed on a routine basis according to a strict schedule based on hours of operation. Scheduled maintenance has proven successful in most cases. In the case of other mechanical platforms, scheduled maintenance also allows for regular inspection of susceptible components. However, there are situations where benefits can be obtained by initiating maintenance actions based on the monitored health of the components. The first is that of condition-based maintenance which for some components can deliver cost savings by eliminating unnecessary maintenance actions. Secondly, fixed period scheduled maintenance does not always catch all potential faults, and a small number of rogue faults could develop into failures between overhauls. For example, for certain safety-critical components such as a helicopter gearbox, this could lead to the total loss of the aircraft.
A diagnostic technique such as wear debris analysis has been used to help identify damage, cracking or wear of components in need of replacement. More particularly, wear on mechanical components usually creates debris that can be detected and analysed to identify its origin. However, a difficulty in relying on debris analysis is that debris may remain undetected when trapped within various niches of a mechanical system. Excessive debris that remains undetected could also cause collateral damage to other components of the system. Another problem with the reliance on the detection of wear debris is that some faults, such as cracking, do not generate much (or any) debris until catastrophic failure is imminent, thus making the technique not useful against such modes of failure.
Another diagnostic technique involves vibration analysis of components. However, vibration analysis is generally less successful than debris analysis because a bearing fault often produces little or no discerning vibration.
It has been recognised that a precursor to a complete mechanical failure of bearings and/or gears is over heating, stress fractures or deformation of the components. A risk that is inherent with current practices is that the precursors or telltale signs of a mechanical failure may go unnoticed during routine maintenance or that there may be failure in the period between scheduled servicing. As a result, despite the most vigilant maintenance schedules, complete mechanical failure can, and still does, occur which can lead to unscheduled downtimes, expensive replacement of machinery and/or components or, in the case of aircraft, a loss of life.
It is therefore an object of the present invention to devise an alternative means for monitoring the mechanical health of mechanical components that can complement existing maintenance practices.